hexagon: Fix build failures in linux-next

hexagon:defconfig fails to build in linux-next since commit 332fd7c4fef5
("genirq: Generic chip: Change irq_reg_{readl,writel} arguments").

The primary build failure is

arch/hexagon/include/asm/cacheflush.h: In function 'copy_to_user_page':
arch/hexagon/include/asm/cacheflush.h:89:22: error: 'VM_EXEC' undeclared

This is the result of including of <linux/io.h> from <linux/irq.h>,
which is now necessary due to the use of readl and writel from irq.h.
This causes recursive inclusions in hexagon code; cacheflush.h is included
from mm.h prior to the definition of VM_EXEC.

Fix the problem by moving copy_to_user_page from the hexagon include file to
arch/hexagon/mm/cache.c, similar to other architectures. After this change,
several redefinitions of readl and writel are reported. Those are caused
by recursive inclusions of io.h and asm/cacheflush.h. Fix those problems by
reducing the number of files included from those files. Also, it was necessary
to stop including asm-generic/cacheflush.h from asm/cacheflush.h. Instead,
functionality originally provided by asm-generic/cacheflush.h is now coded
in asm/cacheflush.h directly.

Cc: Kevin Cernekee <[e-mail]>
Cc: Jason Cooper <[e-mail]>
Signed-off-by: Guenter Roeck <[e-mail]>
signed-off-by: Richard Kuo <[e-mail]>

arch/hexagon/include/asm/cacheflush.h

···
 #ifndef _ASM_CACHEFLUSH_H
 #define _ASM_CACHEFLUSH_H
 
-#include <linux/cache.h>
-#include <linux/mm.h>
-#include <asm/string.h>
-#include <asm-generic/cacheflush.h>
+#include <linux/mm_types.h>
 
 /* Cache flushing:
  *
···
 #define LINESIZE	32
 #define LINEBITS	5
 
+#define flush_cache_all()			do { } while (0)
+#define flush_cache_mm(mm)			do { } while (0)
+#define flush_cache_dup_mm(mm)			do { } while (0)
+#define flush_cache_range(vma, start, end)	do { } while (0)
+#define flush_cache_page(vma, vmaddr, pfn)	do { } while (0)
+#define ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE 0
+#define flush_dcache_page(page)			do { } while (0)
+#define flush_dcache_mmap_lock(mapping)		do { } while (0)
+#define flush_dcache_mmap_unlock(mapping)	do { } while (0)
+#define flush_icache_page(vma, pg)		do { } while (0)
+#define flush_icache_user_range(vma, pg, adr, len)	do { } while (0)
+#define flush_cache_vmap(start, end)		do { } while (0)
+#define flush_cache_vunmap(start, end)		do { } while (0)
+
 /*
  * Flush Dcache range through current map.
  */
···
 /*
  * Flush Icache range through current map.
  */
-#undef flush_icache_range
 extern void flush_icache_range(unsigned long start, unsigned long end);
 
 /*
···
 	/*  generic_ptrace_pokedata doesn't wind up here, does it?  */
 }
 
-#undef copy_to_user_page
-static inline void copy_to_user_page(struct vm_area_struct *vma,
-					     struct page *page,
-					     unsigned long vaddr,
-					     void *dst, void *src, int len)
-{
-	memcpy(dst, src, len);
-	if (vma->vm_flags & VM_EXEC) {
-		flush_icache_range((unsigned long) dst,
-		(unsigned long) dst + len);
-	}
-}
+void copy_to_user_page(struct vm_area_struct *vma, struct page *page,
+		       unsigned long vaddr, void *dst, void *src, int len);
 
+#define copy_from_user_page(vma, page, vaddr, dst, src, len) \
+	memcpy(dst, src, len)
 
 extern void hexagon_inv_dcache_range(unsigned long start, unsigned long end);
 extern void hexagon_clean_dcache_range(unsigned long start, unsigned long end);

arch/hexagon/include/asm/io.h

···
 #ifdef __KERNEL__
 
 #include <linux/types.h>
-#include <linux/delay.h>
-#include <linux/vmalloc.h>
-#include <asm/string.h>
-#include <asm/mem-layout.h>
 #include <asm/iomap.h>
 #include <asm/page.h>
 #include <asm/cacheflush.h>
-#include <asm/tlbflush.h>
 
 /*
  * We don't have PCI yet.

arch/hexagon/kernel/setup.c

···
  */
 
 #include <linux/init.h>
+#include <linux/delay.h>
 #include <linux/bootmem.h>
 #include <linux/mmzone.h>
 #include <linux/mm.h>

arch/hexagon/mm/cache.c

···
 	local_irq_restore(flags);
 	mb();
 }
+
+void copy_to_user_page(struct vm_area_struct *vma, struct page *page,
+		       unsigned long vaddr, void *dst, void *src, int len)
+{
+	memcpy(dst, src, len);
+	if (vma->vm_flags & VM_EXEC) {
+		flush_icache_range((unsigned long) dst,
+		(unsigned long) dst + len);
+	}
+}

arch/hexagon/mm/ioremap.c

···
 
 #include <linux/io.h>
 #include <linux/vmalloc.h>
+#include <linux/mm.h>
 
 void __iomem *ioremap_nocache(unsigned long phys_addr, unsigned long size)
 {